Hello. I have a 2002 A6 3.0 with about 100,000 miles. The car is running well and maintained. Over the last couple of days, I noticed that I hear a tapping(much like the sound of valves in a low oil state) while I am accelerating. Once the RPM's drop, the sound is gone. Does anyone have any suggestions what could be causing this? I added Lucas oil stabilizer, and it helped a little, but the tapping returned. A friend with auto tech experience suggests I add Seafoam to the oil, drive the vehicle for about 50 miles to clean any gunk off of the valves, and then change the oil. If anyone has any suggestions, I would really appreciate it.

 

Agreed on half a can of Seafoam in the oil and also look around the engine bay and make sure nothing is interfering with the moving assemblies on the engine. Have the ECU scanned for pending codes as well - there may be something in there that hasn't tripped the CEL. Throw a full can of Seafoam in the gas tank as well, and verify the proper gaps on the spark plugs - if it's knock, it could be from fuel or ignition issues.

 

Thanks for the advice. I'll give it a try.